Use deglob instead of recursive readdir

[AlahmadiQ8]

This PR replaces the library recursive-readdir with deglob. The major advantage are the following:

• deglob respects .gitignore. It will read .gitignore file and ignore all the patterns in there in the result.

That means now when you use the plugin, no need to duplicate ignore patterns in the .gitignore. This is useful since ignoring files in the gitignore is probably most people's use case.

To opt out of using .gitignore, you can pass in the useGitIgnore: false config option.

Example:

    new UnusedWebpackPlugin({
      // Source directories
      directories : [path.join(__dirname, 'src')],
      // Exclude patterns
      exclude     : ["**/__tests__"],
      root : __dirname,
      useGitIgnore: false   // true by default 
    }),

Please let me know what you think :)

[MatthieuLemoine]

@AlahmadiQ8 Great idea & nice work!

I've just setup the CI. Can you fix the conflicts ?

[MatthieuLemoine]

To pass the CI checks you need to make jest, eslint & prettier happy

[AlahmadiQ8]

Thank you so much :)! merge conflicts fixed